Over the past several years, the rapidly increasing traffic volumes carried by telecommunication networks have been clearly observed as a result of the bandwidth-intensive applications such as Internet access, electronic commerce, multimedia applications, and distributed computing. Optical telecommunication systems employing optical fibers as the transmission medium have exhibited a superior performance/cost ratio for both long-haul and short-haul routes compared to any other type of telecommunication systems. In particular the emerging dense wavelength-division multiplexing (DWDM) and all-optical network communication systems have shown a way to provide high-speed and large-bandwidth network services at low cost for both long-haul and metropolitan networks. As the DWDM networks are deployed, it becomes necessary to improve the delay, bandwidth, and connectivity of optical telecommunication networks, as the information system's subscriber growth continues unrestrained.
Although telecommunication service providers have increasingly deployed fiber optic cables for both long-haul and short-haul routes, the ever-increasing network traffic has created some constraints on communication network in terms of speed, capacity, and connectivity of networks. Telecommunication service providers generally address these speed, capacity and connectivity constraints by either installing new fiber cables or by expanding the transmission capacity using faster devices or DWDM techniques. The formal method is quite expensive and difficult, as it requires a huge investment as well as constant upgrade of the existing fiber network infrastructures. In the latter methods, the DWDM increases the number of optical signals, called channels, transmitted simultaneously on a single fiber, whereas the time-division multiplexing (TDM) increases the transmission speed of optical signals. The DWDM is ideal for high-capacity networks such as point-to-point or backbone ring networks with minimal switching and routing requirements. However, in the emerging DWDM metropolitan and local area networks, the major concern is not the network capacity but the reconfigurable network connectivity. In any way, for both DWDM and TDM methods, the fiber optic switching will become a major issue for optical telecommunication systems. Ever since the fiber optic telecommunication technology was first available, many network managers preferred all-optical network due to its benefits in terms of bandwidth, security, and segment length. The OXC networks can also improve the efficiency of all-optical network by providing a “transparency” to modulation format, protocol and signal bit rates. Without the all-optical networks, the signals of telecommunication networks must be converted from optical to electrical form at switching ports and the routing information in the information packet should be analyzed and utilized for a propel signal routing. Then the signal must be converted to the optical form for a subsequent signal routing and transmission. These optical-to-electrical and optical-to-electrical signal form conversions reduce the over-all network efficiencies as it introduces delays and noises.
It is widely believed that the DWDM network is an enabling technology for Internet applications, as the expectations of the Internet's great potential will not be realized without the bandwidth gain provide by DWDM. Direct fiber optic switching without electrical-to-optical or optical-to-electrical conversions is much needed for the all-optical DWDM network. The unprecedented record of growth being generated by Internet traffic and a tremendous amount of data being dumped on the public network show no sign of slowing yet. Without optical telecommunication network and optical fiber's enormous bandwidth potential, the Internet performance will be significantly slowed as the subscriber growth increases unrestrained. Notably there is a need for fiber optic switches for all-optical DWDM networks, which can provide low cost, small crosstalk, reliable, compact, reconfigurable, modular, scalable, high speed, and wavelength/polarization insensitive characteristics.